Let's say the following is being returned when issuing a RabbitMQ command, such as rabbitmqctl status.

~]# rabbitmqctl status
Error: unable to perform an operation on node 'rabbit@server1'.

If the output also includes the following, this means that the RabbitMQ CLI tool was able to establish a TCP connection to the RabbitMQ node, but there was some authentication failure.

* TCP connection succeeded but Erlang distribution failed

RabbitMQ Server is down

The RabbitMQ server may not be running. Use the systemctl command to determine if the RabbitMQ Server is running. If the RabbitMQ server is not running, try to start the RabbitMQ server.

~]# systemctl status rabbitmq-server
● rabbitmq-server.service - RabbitMQ broker
   Loaded: loaded (/usr/lib/systemd/system/rabbitmq-server.service; enabled; vendor preset: disabled)
   Active: activating (auto-restart) (Result: exit-code) since Tue 2022-08-09 03:33:59 CDT; 6s ago
  Process: 56458 ExecStart=/usr/sbin/rabbitmq-server (code=exited, status=1/FAILURE)
 Main PID: 56458 (code=exited, status=1/FAILURE)
   Status: "Standing by"

SSL

If RabbitMQ is configured to use SSL, this error can occur if there is some issue with the SSL configuration, such as an expired certificate in the ssl_options.certfile or ssl_options.cacertfile being used. Refer to RabbitMQ - SSL/TLS.

Remote node is down

When attempting inter-node communication, such as issues a RabbitMQ command from "node a" to "node b", ensure the RabbitMQ server is up and running on both nodes.

Erlang

When attempting inter-node communication, such as issues a RabbitMQ command from "node a" to "node b", the Erlang cookie being used by the nodes must be identical. Refer to RabbitMQ and the Erlang Cookie.